Simplify blosc build configuration by turning it into an object library

[rroelke]

The external blosc library is used in the byte shuffle filter. Our build system contorted itself a bit to compile this into TILEDB_CORE_OBJECTS as well as the unit test. As this pull request shows there is a much simpler path.

While I no longer have need of the reason I implemented this, it is nonetheless a simplification of the build process, so I figured I'd post a PR for it.

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TYPE: NO_HISTORY
DESC: Simplify blosc build

[davisp]

Looks good overall except you need to go through and add the blosc object library dependency to all the tests that need it. I'm pretty sure my 65154 branch has those listed out. Alternatively, the way I fixed those was to just run make -j$(nproc) tests && VERBOSE=1 make tests over and over fixing each link error until the build succeeded.

[davisp]

Also, I'll note that given we don't really need to make this change, it might not really be worth the churn. Though I do agree it does simplify things which is always nice.

[rroelke]

Also, I'll note that given we don't really need to make this change, it might not really be worth the churn. Though I do agree it does simplify things which is always nice.

Given that we have to add it to all the unit test object library lists - which I didn't expect, I though that it would be enough to include it in the filter object library - I'm not sure this is worth doing anymore either. I might close it.